Figure 5: Signal to noise plot for the spike-in data under three transformations. Spiked-in genes are high- lighted in red. The horizontal axis is the binned gene specific variances while the vertical axis for the plots in the left column is the average expression across the two groups (abundance) while it is the the average dif- ference in expression (signal) for the right column. The apparent relationships between abundance and noise and signal and noise clearly change dependent on the transformation used. While conjugacy appears ap-propriate for the raw data, and independence relationship appears more appropriate for the log-transformed data.